Control mechanism for grinding machines



Aug. 23, 193 P. PLANTINGA CONTROL MECHANISM FOIL- GRINDING- MACHINES Filed Sept. 50,1930 9 Sheets-Sheet l Aug. 23, 1932.

P. PLANTINGA CONTROL MECHANISM FOR GRINDING MACHINES Filed Sept. 50. 1930 9 Sheets-Sheet 4 Rs & A. m N W 0w V\ r 4 Jerk/17 Aug. 23, 1932. P. PLANTINGA CONTROL MECHANISM FOR GRINDING MACHINES Filed Sept. 30. 1930 g- 1932. P. PLANTINGA CONTROL MECHANISM FOR GRINDING MACHINES Filed se i. so, 1950 9 Sheets-Sheet 6 QQN \Q. & m .g p g mm g as ks hhhhhhhhii hdezzr @ff/ZF/kiZ/W Aug. 23, 1932. P. PLANTINGA CONTROL MECHANISM FOR GRINDING MACHINES I Filed Sept. 30, 1950 9 Sheets-Sheet 7 III! II I Nbw lllllllllllli 31 Q MKN 9 Sheets-Sheet 8 Aug. 23, 1932.

P. PLANTINGA CONTROL MECHANISM FOR GRINDING MACHINES Filed Sept. 1930 g- 1932- P. PLANTINGA CONTROL MECHANISM FOR GRINDING MACHINES Filed Sept. 30. 1930 9 Sheets-Sheet 9 mmN - mechanism, lookingin the direction of the f Patented Aug. 23, 1932 UNHTEDFSTATES PETER PLANTINGA, or 'GREENFIELD, raAssAoHusE'rTs, AssrGNoB TO GBEECNFIELD TAP & DIE CORPORATION, MASSACHUSETTS or GREENFIELD, massacswsnrrs, A oonroanfrron or CONTROL MECHANISMS F612. GRINDING MACHINES 1 Application filed September 30,1930, Serial no. 485,473.

This invention relates to internal grindingmachines and particularly to mechanism for controlling certain operations thereof.

It is the general object of my invention to provide improved control mechanism by which certain successive steps relative to internal grinding may be more effectively performed.

An important feature of my invention relates to the provision of means for effectively initiating a truing operation after the rough grinding of the work has been performed.

A further object of the invention is to provide mechanism for disengaging the feeding mechanism after the finish grinding is completed and for withdrawing the grinding wheel from the work. 1

My invention further relates to arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appended claims.

A preferred form of the invention is shown in the drawings, in which i Fig. 1 is a sectionalside elevation ofthe cross feeding mechanism of an internal grinding machine.

Fig- 2 is a sectional front elevation, taken along the line 2-2 in Fig. 1;

Fig. 3 is a detail front elevation of certain parts also shown in Fig. 2;

Fig. 4 is a detail sectional plan view, taken along the line 44 in Fig. 2; i

Fig. 5 is a plan view of certain feed pawl arrow 5 in Fig. 2;

Figs. 6 and 7 are front elevations of certain parts, looking in the directions of the arrows 6 and 7 in Fig. 5;

Fig. 8 is a sectional elevation of certain hydraulic actuating mechanism for the feed pawls, taken along the line 88 in Fig. 24;

Fig. 9 is a sectional end elevation, taken along the line 9-9 in Fig. 8;

Fig. 10' is a plan view of a transmitting member in the feed pawl mechanism;

Fig. 11 is an end elevation. looking in the direction of the arrow 11 in Fig. 10;

Fig. 12 is a'sectional front elevation of certain control mechanism to be described;

Fig. 13 is an end elevation thereof, partially broken away,and looking in the direc- .tion of the arrow 13 in F ig. 12;

Fig. 14 is a sectional side elevation of cerline 14114 in Figs. 12 and 15 the arrow 15 in said figure, and taken along the line 15 -15 in Fig. 24;

Fig 16 is a detail plan view, looking in the direction of the arrow 16 in Fig. 14;

Fig. 17 is a detail sectional plan View,

along the line 1717 in Fig. 14;

,tain cam feeding mechanism, taken along the Fig. 18 is a sectional rear elevation, taken alongthe line 1818 in Fig. 12; V Fig. 19 is a detail plan view, lookinginthe direction of the arrow 19 in Fig..18 C

Fig. 20 is a side elevation of aloam lever taken along the line 20 20 in Fig.21; v

Fig. 21 is a side elevation, partly in section,

and clutch control parts, partly in section and I of certain clutch and control mechanism. for

controlling the return feed of the grinding wheel;

, Fig. 22 is a side elevation, partly in section,

of additional control mechanism;

Fig. 23 is a detail sectional view, taken along the line 23423 in Fig. 22;

Fig. 24 is a plan view, partly in section, of

detail front elevation, par,tly

Cal

trolling the hydraulic table mechanism in such amachine is shown and described in a prior 'Drake Patent No. 1,817,180, issued August 4, 1931. g

: Briefly described, the machine to 'which'my improvements are applied is an jintern'al grinding machine in which the work is sup verse orcross feedingadjustmentradially of the @work, and the work,-as previously stated, is mounted for reciprocating axial movement relative to the grinding wheel. 7

Suitable provision is made for rotatingthe work and grinding wheel at desired speeds.

The control devices of-the machine'are so designed that rocking of the control handlein one direction after the. rough-grinding is completed will increase the table traveland efi'ect relative rearward movement of the "wheel'andwill also'reduce the speed of table travel. This increased rearward travel car- :Eriesth'e grinding wheelv pastthe truing device "andcaus'es the wheelto be suitably dressed forthe'fin'ish grinding operation.

.As soon as the handle is released or restored-to 'normal pos1t 1on, "the table resumes its reciprocation "between normal -grlnding "limits but continues r to travel .at reduced speed until the finish grinding is completed.

Manual rocking .ofithe control handle in the opposite direction then increases the table travel-"Ito withdraw the wheel .a shorter distance from'ithe work, restores the normal rate oftable travel, and brings the'table to rest with the wheel *withdrawn so that' the work may ibe' removed and replaced.

:My present inventionrrelates more particula'rl-y tothe 'provision of'mea'ns by which the tzible control devices may be automatically or semi-automatically actuated, by which the cross fee'd may be automatically regulatedfor the different steps in the "grinding'opera tron,- an'dby which the A grinding wheel may .be removed radially inward "from the work when the grinding operation -is completed. Gross-feedingme0hanism I will first describe briefly'the mechanism for feeding the grindingwheel transversely towaiid'onfromthe revolving iwoi'k. .Refernng'particularly to Figs. 1 and '2,ja cross feed shaft 30 is mountednatitsouter end in a;

fixed bearing 31- and: is provided with a disc 32 fixed to said shafftand having'a ratchet *W-hel'33 an d'ring gear 34 mounted thereon. The shaft 30 is efiective to move the wheel "slide 'through-any "usual operating connections or gearing not shown.

Anouter flange3'5 of the'disc 32 also forms a gear -engaged by'a pinion 36 mounted in a'hand --wl1eel37 andnormally 'held from relative rotation therein. The pinion 36 may be turned manually by ahandle 38 when relativeadjustment of the hand wheel and di'sc' 32 is desired. A cam ring 40 is mounted on the hand wheel 37 and is moved angularly therewith.

A feed pawl 41 (Figs. 1 and 2) is fixed to a stud 43 pivoted in a pawl carrier 44 slidable on parallel rods 45. A second pawl 42 is loose on the stud 43., A spring 46 (Fig.

2) is connected to a stud 47 (Fig. 5) fixed inthe pawl 41 and projecting loosely into an enlarged'opening in the pawl 42. The spring 46 has .:a rearwardly projecting end 48 engaging the back edge of the pawl42.

The pawls are so arranged that the point ofonepawlis half toothto the rear of the point of the other pawl, so that a hall" toothdieed'can betaken if desired. The carrier 44 is forced rearward or to the right in Figs. 2 and 5by a coil spring 50 (Fig. 5). An upwardly projecting arm 52 (Figs. 2 and 5) is formed as partof a bell crank 53 mounted on a pivot stud 54. The arm 52- engages-the rear. end of the pawl carrier "44 and the'ilaterallyprojectingarm of the bell crank 53 is provided with a cam roll rier is fixed and consequently the rate of cross feed is determined by the steps on the cam [.10. 'Each crossfeeding. movement at the beginning ofthe grinding operation is fairly large, but the extent of movement-is progressively decreased .as the grinding .approaches finish s1ze.

' iPa'wZ carriageactuati ng mechanism The'mechanism for giving the pawl carriage or carrier 45 its. feeding movement is "best shown in Figs. 8 to 11. A rocker 57 (Fig. 10) is loosely-mounted on the pivot stud'54ipreviously described and is provided with an adjustable contactscrew 60 adapted toengage the rear face of the upwardly extending arm 52 of the bell crank 53 (Fig. 2).

'A' portion 61 (Fig.1l) of the roclzer57 is positioned above a stud '62 adjustably se-' cured in the upper end of a piston rod 63 (Fig. 8.) connected toa piston 64 yieldingly pressed downward in a'cylinder 65 by a coil spring 66; v

.A pipe 67 ig. 8) is connected to the lower end-of the cylinder 65 below the piston 645and the pipe 67 is connected at its opposite end to ports 68 and 69 in a valve casing '70. vAtpiston valve 71 is slidable in the easing'70 and is connected by a rod 72 and arm 73 to a lever74 and cam roll 75 positioned for engagement by a cam block or dog-76 adjustably secured to the side of the table T. he valvecasing 70is provided with an inlet 77 for a suitable pressure fluid and with an outlet or exhaust. 78.

When the table T approaches its limit of travel in a given direction, the dog or cam block 76 depresses the lever 74 and connects the port 68 to the inlet pipe 77. Fluid under pressure is thus admitted under the piston 64, raising the contact screw 62 and swinging the rocker 57 to advance the feed pawls and turn the cross feed shaft any predetermined amount. r

i As soon as the piston 71 is released, a coil spring? 9 (Fig. 8) returns the piston to the position shown in Fig. 8, with the port 69 connected to the exhaust 78., A suitable bleed opening 80 is provided in the side of the cylinder 65 to take care of any leakage past the piston 64.

During the normal operation of thema chine, the feed pawls are thus actuated hydraulically by mechanism controlled by the table dog 76, but the extent of each feeding movement is controlled by the cam ring 40.

Automatic control mechanism which the sequence of operations of the ma chine is automatically controlled.

Referring particularly to 2, 12 and 18, a disc or plate 82 (Fig. 12) is provided with a hub portion 83 which is rotatably supported on a stud 84 fixed in a frame member 85 and standing perpendicular to the axis of the cross feed shaft 80.

The disc 82 is frictionally held from accidental movement by a friction collar 85 keyed to the end of the stud 84 and forced yieldingly against the outer side of the plate by I a spring 86 seated in a recess in a cap or nut 87. A ratchet wheel 88, a cam plate90 and a second cam plate 92 are all fixed to the plate 82 and are rotatable therewith.

A yoke 94 is loosely mounted on the hub 83 between the disc 82 and the ratchet 88. The yoke 94 is provided with'a feed pawl 95 (Fig. 14) yieldingly pressed against the ratchet wheel 88 by a spring 96. One end of the yoke 94 is slotted at 97 (Fig. 14) toreceive the flattened end of a stud 98 mounted in a carrier 99 slidable on fixed guiderods 100. A spring 101 on the lower end of one of the guide rods acts to yieldingly return the carrier and feed pawl to initial or upward position. I

A plunger 102 (Fig. 15) is secured toan offset portion 103 of the carrier 99 and is provided at its lower end with a piston 104 slidable in a cylinder 105.

A spring 106 is inserted in the lower end of the piston 104 and assists the spring 101 in moving the carrier 103 and associated parts upward. i

The cylinder has an inlet passage 10? through which a fluid under pressure may be admitted to the upper part of the cylinder, thus foroingthe piston 104 downward erates the cross feedpawls. Consequentlyh' the cross feed pawls 41 and :42 and the pawl 95 are actuated simultaneously under the coin trolof-the table dog 76 (Fig. 8).

A second feed pawl 110 (Fig. 14) is pivoted on the opposite end of the yoke 94 and 2.

engages the; ratchet wheel 88 at a point substantially opposite to the pawl 95. A stop screw 111- is threaded in a lug 112 on a rearward extension of the'pawl 110 and engages a shoulder on the yoke 94a iA spring 113 1...:

mounted on the end of the yoke 94 engages the lug 112 and yieldingly holds the screw 111' incontact with the shoulder on the yoke 94. The screw 111 is so adjusted that when the screw en a es the shoulder the awl-z b O 7 110 will be out of engagement with the teeth of the ratchet Wheel 88. I i

A-plate 114- (Fig. 16) is secured to the rear side of the pawl 110 and is provided with an I angularly disposed flange 115 (Fig. 14) I will now describe the mechanism by adapted under *certain circumstances to be engaged by a positioning device mounted on the cam ring 40. r This comprises. a-"contact member 116 (Fig. 4) pivoted at 117 on a bracket 118 which in turn is secured to the side of the cam ring 40 by screws 119 (Fig. 2). The member 116 is loos'elymountedon the bracket 118 but is held yieldingly in midposition by a pair of leaf springs120 (Fig.-

Operation of ratchet mechanism QThe rat'chetjw-he'el 88 (Fig. 14) is provided with dwell portions 88 at three points inits periphery'p Thefeed pawl 95 isregularly actuated and feeds the ratchet wheel '88 apredetermined number of teeth at each actuation until the pawl "95 encounters oneofthe dwells or blank portions 88. i The rate offeed may be controlled by an adjusting screw 122 (Fig. 14) which limits the return movement of the pawl 95. During this normal operation of the ratchet wheel, the second feed pawl 110 is inoperative The parts 'are soarranged that the pawl 95 will engage one of the'dwells or blanks 88 jat the end of each grinding operation, after which no movement of'the ratchet wheel 88 can take place until thecam ring40 has been rotated to a point where the contact Inember 116 engages the flange 115 and'de presses the'pawl 110 until it engages the teeth of the ratchet 88. e

The springs 1 20 (Figs. 2 and 4) permit the member 116 to yield in either direction if movement of the pawl 110 is obstructed, but

these springs 120 are strong enough to over.- come the ordinary resistance.ofthezspring 118 previously described.

The pawl llQ'Will then advance the ratchet wheel a suflicient distance to carry the blank fljanother blank appearsunder-the pawl "95,.

90; and 92.

.It will ,thusappear. that afterthe cam ring -40:-has;been giv-en a definite amount of angular movement,zthe ratchet wheel ,88 will be startcdand xwillpbe rotatedthrough 120, carryingwith it; the disc .82 and cam;.p lates :"Table control in echa n i san. 7 1 will .now describe the mechanism by .which: the. table is given an increased travel :afterthe rough-grinding has been completed and-by:v'vhiclr the grinding wheel and truing 7 device are brought into operative relation.

, engagement with one of the lugs 125, the p Referring to F igs.,12 and 22,1a ring 122 is secured to the face of the disc or plate 82 byscrews 123 (Fig. 23) extending through segmental slots 124 inthe ring 122?. The ring 122*; is thns angularly adjustable within limits on; the plate182.

The ring 122 is provided with three equally spaced lugs :or projections 125 (Fig. 22) positioned; to engage a cam plate126 secured tog-the, upper end of a lever 127 mounted on -,a fixed pivot 128.. A contact screw 129 is adjustablysecured ina depending arm 130 of .thejlever 127 and engages theend of apis- =ton=-valve-132slidable in a valve cylinder 133.

A supply pipe 135 (Figs. '22 and 24) is connected to one portion of the valve chamber l33andan exhaust pipe 136 is connected to the opposite end of the valve chamber.

.Perts .137 :are connected t rough an opening l 38' to-a' pipel39'(Figs. 24 and 26) the other end of which is connected to the end of a cylinder 1 10.. A A piston 141 (Fig. ,26) is slidable in th cylinder '14OJand {is ryieldingly-held in the position shown by a spring 141*. A piston rod142;is. actuated by the; piston 141 and is connected through a link 143to a member 'l44,loosely pivoted on the control shaft'145 by which'the hydraulic table mechanism is controlled. A handle 146 is mounted on the end vof'the-shaft and is engaged by; an adjustable-contact screw 147 in-an upward extension; of the-member 144. l :Whenthe-lever 127 (Fig. 22) is rocked by pistonuvalve132 is pushed inward, connecting-the pressure'inlet 135-tothe pipe 139 and-"thus ,adniittingfiuid under pressure to the end of the cylinder 140 (Fig. 26).

The piston 141, piston rod 142 and link 143 .aretherenpon moved to-the left in Fig. 24, causingutheacontact screw 147 to engage the handle146 andv rocking the handlein the direction-ofthearrow a in Fig. 25.

When the handle and control shaft are thus rocked, certain control mechanismis set'in operation by whichthe=work1table is given vice.

:an increased travel which effects a relative withdrawal of the wheel rearward from the work and into engagement witha 'truing de- At the same time the rate of table travel is reduced. After the wheel isdressed, the table returns to its normal limits of tra'vel but still at reduced speed. i

The control mechanism by which these operations are effected forms no part of my present invention and is fully shown and de- For the purposes of this application itis suflicient to state that rocking of the control scribed in the said prior DrakePatent No.

handle 146 in the'directionofthe arrow'a in Fig- 25 will cause the control mechanismto operate as above described.

It is sometimes desirable to utilize the other parts of myinvention without automatically actuating the handle 146. preferably form the link 143 in telescoping parts, normally connected by a cross-pin'148 (Fig.24). If itis desired to disable the'automatic connection to the table control mechanism, I remove the cross-pin 148 and place it in auxiliary openings 149 (Fig. 25), in

.which position the two parts of the link 143 telescope idly and without moving the member 144 or handle 146.

Reeerse'feed mechanism After the wheel is dressed, the grinding wheel is given a predetermined number of passes over the work, the number of passes being determined by the setting of the feed pawl 95. It is then desirable: to reverse the cross feed and .to withdraw the wheelradi- 150 is fixed to the stud 43 to which the feed pawl 41is also secured and on which the feed pawl 42 is loosely mounted.

The outer end of the lever 150 is provide with a face 151 (Fig. 6) underlying anarm 152 fixed to the end of a rod 153 slidably mounted in a fixed bearing 154. An arm 155 is fixed to the opposite end of the rod 158 and is provided with a cam roll 156 positioned to engage the ca1n'92 (Fig. 13) previously described. equally spaced raised portions 92*, as indicated in Fig. 13.

When the cam roll 156 engages one of the depressed portions of the cam 92, the arm 152 is raised bya spring tobe described and Consequently I .1

The cam 92 is formed with three lzlii the feed pawls 41 and 42 are free to engage to be started on new piece of work, a lug 160' (Fig. 2) is mounted on the side of the cam ring in position to engage the downwardly extending arm of a lever 161 (Figs. 2 and 3) loosely mounted on the pivot stud 54.

An upwardly extending lug 162 (F ig. 3) of the arm or lever 161 engages an outer face of the arm 152. When the lug 160 engages the lever 161, it turns the lever in the direction of the arrow?) in Fig. 3 andpushes the arm 152' and the rod 153 to the right, as viewed in Figs. 2 and thus releasing the arm 150 and feed pawls 41 and 42.

A spring 164 (Fig. 2) acts to force the rod 153 yieldingly'to theleft in Fig. 1 and also to turn the rod 153 to hold the roll 156 in yielding engagement with the cam 92. When the rod 153 is pushed to the right by the lug 160 operating through the connections above described, the roll 156 will be carried beyond 7 the cam 92 to the position shown in. dotted lines in Fig. 5, whereupon it will swing downward until a stop screw 165 (Fig. 5) in a lug 166 on the hub of the arm 155 engages a pin 167 mounted in a fixed lug 168.

VJ hen the lug'16O passes the arm 161, the

,. arm. 152 and rod 153 will bereleasd but re-. turn movement thereof will be prevented by engagement of the roll 156 with the side of the raised portion 92 of the cam 92 on which the roll had previously rested.

The arm 152 will thus be held in inoperative position until the cam 92 has been rotated a sufficient distance to remove the raised portion 92 out of alignment with the roll 156, the roll then entering the next low part of the cam but remaining inoperative until the next high part 92 is reached.

In the usual starting operation, the ratchet wheel 33 and cam rlng 40 are manually rotated in an antl-clockwise direction to move the wheel radially outwarduntil it engages the work. By such manual rotation, the lug 160 is caused to engage the arm 161 and release the feed pawls for renewed operation without any particular attention from the r o erator. p

Reverse cross feed dm'oe The reverse cross feed driveis best shown on Figs. 18to 21. A collar 170 (Fig. 21) is fixed to a short shaft 171 rotatable in a fixed bearing 17 2 and having a pinion 17 3' engaging the ring gear 34 (Fig: 1): previously de-- scribed asmounted to rotate with thecross V feed shaft '30. i x p Aishaft 175 (Fig. 21) is mounted to rotatein alignment withthe short shaft 171 and is provided with a gear 176 engaged by a wide faced pinion 177 on a countershaft 178 which may be continuously driven by a belt179 on a pulley 180.

: An elongated sleeve 182 (Fig. '21) is fixed to'the shaft 175a'nd is slidable in a bearing.

183. The sleeve 182 is provided with clutch teeth at" outer end positioned to engage similar teeth on described.

A spring 184tends to move the sleeve182 yielding'ly toward clutch-engaging position and such movement is normally opposed by a cam roll 185 mounted on an arm 186 and engaging a flange 187 on the sleeve 182; The

arm 186 is mounted on a short pivot shaft the collar 170 previously 188, to the opposite end of which an arm 189 p is secured. Cam-engaging blocks 19,0 and 191 are secured to the end of the arm 189.

The block 190 is permanently positioned thereon and the'block 191is adjustable along the arm relative to the block 190. By such.

adjustment, the effective width of the camengaglng face may be varied.

The blocks 190 and 191 are positioned to engage the cam previously odescribed (Figs. "12 211N118), which cam is provided with three equallyi spaced recesses 90.

When the cam blocks 190' and 191 drop into" on of the recesses 90 thespring 184 (Fig. 21) moves the shaft 175 and sleeve 182 endwise to engage the clutch teeth and'causes the pinion 173 to rotate thering' gear 34.and

cross feed shaft 30 until the [cam 90 has turned through a sufficient angle so thatthe cam blocks 190 and 191 are forced out ofthe recess 90*, atwhich point engagement of the.

clutchteeth is interrupted. Theamount of rotation maybe determined by adjusting the block191 toward or away from the block 190.

WVhile the reverse movement of the cross feed shaft above described is not very rapid, it is greatly increased over the rate of feed' to be obtained by the use of the feed p-awls 40 and 41 and quickly removes the grinding wheel inward from finishgrinding position and to a position in which the wheel clears the work, where it will be reciprocated idly until the operator stops the table movement for changing the work. a

A shield 200 (Figs. 1 and 2) is ounted on the cam ring 40 to positively disengage the ratchet feed when the cam ring rotates beyond a predetermined point. 7 An index arm202.,(Figs. 5 and 7 may be secured to-the frame member 154 and may be provided with a pointer 203 cooperating with an index line 204 on the outer face of each cam lug 125. This index line and point er are useful when operating themachine' :40: H V I mg proceeds and approaches finish size.

1 88 andis accordingly inoperative.

non-automatically, aswhen the link 143 (Fig.

) is, disabled removing the pin 148. Under these circumstances, the operator may watch the index lineg204and will-throwover I 146 (Fig. 25) as soon as'the index line204 reaches the pointer 203.

7 Operation Having described the details of construetion of my improved control mechanism, the

' method-of operating the machine'is as fol lows v After a grinding operation is completed,

the operatorthrows the handle 146 (Fig. 24) to the left and brings the table to rest with the grinding" wheel withdrawn from the work but in advance ofthetruing device. At this time the feed pawl95 (Fig. 14) rests upon one. ofthe blankspaces of the ratchet wheel Furthermore, the roll 156 (Fig. 22) rests upon one of the high points 92? of the cam 92 and holds thefeed pawls41 inoperative, with the grinding wheel substantially spaced i nwardfrom grindingposition. 7

After the work is changed, the operator turns the ratchet wheel 33 andcam ring in an anti-clockwise direction by means of the ha-ndle in thehand wheel 37 until the grinding wheelisinoved outwardjand engages the interior of the hole to be' ground.

During this movement of the camring 40,

' theflug .160 (F ig; 2.) engages the lever 161 and in afew ten thousands of finish size, the mem releases the feed pawls for renewed operation asabove'jdescribed.

Intermittent feeding movements of the pawls41 and 42 then commence, advancing the ratchetwlieel 33 and cross feed shaft 30 by amounts determined by the camring 40,.

thera-te offeedbeingred'uced'as the grind- After the grinding has proceeded to with ber. 116 (Fig. 2) renders the auxiliary pawl 1 10 (Fig. 14) operative and this pawl advances; thefratchetwheel 88 far enough to remove thev blank space from under the regular ratchet feedv pawl 95, which thereafter continues the rotation of the ratchetwheel88. Byfsuch rotation, one of thelugs 125 (Fig.

" 22) operates'through the lever 127. to actuate the'piston 141' (F ig..26) and'move the handle 146 24) to the-right, causing the table valve control nie'chanism to give the table an increased rearward travel and bring the wheel into the range of the wheel truing device, such I thejfinish grinding proceeds for a predeincreased travel being at reduced speed.

The table valve control mechanism thereafter automatically restores the travel to normal limits but still at reduced'speed, and

t ermined number of passes.

During this finished grinding, the roll (Fig. 2) reaches the highest stepof the cam ring-Q40 the feed pawls, .41 and 42 take a half tooth only. The: feed continues atthis rate 'for. fewpasses until the shield-200 comes underthe feed-pawls, which then become inoperative,.so that no. further cross feedtakes place. After a-number of passes without feed, the roll 156 (Fig. 5.) is, engaged:

by a high point-ofthe cam 92, and raises the pawls 41 and 42 from the shield 200, in which raised position they are, retained until released.

The cam blocks 190 and 191 (Fig, 18 then drop into a recess inthe cam permitting; the reverse clutch to engage, and the cross] feed ratchetwheel is then reversely rotated. at; substantial speedto withdraw the grind-- ingwheel quickly inward away from the finished internal ground surface.

The feedpawl (Fig. 14) then encounters the next dwell or blank 88 on the ratchet wheel 88 and the table continuesto. reciprocate. with the partsin inoperative relation until the reciprocationis stopped the operator for changing the work.

I am thus able to performrough and finish grinding operations with an intervening wheel truing operation. without attention by the operator,..and duplicate work of great the connection. to the handle 146.. When. operating semiautomatically, the (operator watches the indexline. 204. (Fig. 5.) and throws overthe handle 146 manually when the index line 204 reaches the pointer- 203. The t'ruing. mechanism is thus set in operation, causing the wheeltov be, dressed during an increased rearwardftravel of the work, after which the wheel returns automatically. to its grinding range and completes the finish grinding as previouslydescribed.

With either method of operation, the workman will manipulate the handle 38 at some time during; the rough-grinding operation,

thereby compensating forthe wear of. the- Wheel during rough-grinding. This feature of my invention is fully'descrilied and the operation thereof explained in detail in my companion application Serial No. 485,472,

filed Sept. 30, 1930.

Having thus described my invention and the advantagesthereof, I do. notwish to be' limited to the detailsherein disclosed, otherw1se-thana s set forth in the claims, but. what I claim is changed to meet different working mechanism to feed said 1. In a grinding machine having a table, mechanism for reciprocating said table and a control device therefor, a grinding wheel and cross feed mechanism therefor, in combination, means to actuate said cross feed grinding wheel, and mechanical control mechanism rendered operative by a predetermined operation of said cross feed mechanism and effective to cause subsequent movement of said control device and to thereby modify the table travel, said control mechanism including a ratchet wheel and a feed pawl associated therewith and means to render said feed pawl operative to turn said ratchet wheel and thereby effect movement of said control device after a predetermined actuation of said cross feed mechanism.

2. In a grinding machine having a table, mechanism for reciprocating said table and a control device therefor, a grinding wheel and cross feed mechanism therefor, in combination, means to actuate said cross feed mechanism to feed said grinding Wheel, mechanical control mechanism rendered operative by a predetermined operation of said cross feed mechanism and effective to cause subsequent movement of said control device and to thereby modify the table travel, said control mechanism including a ratchet Wheel and a feed pawl associated therewith and means to render said feed pawl operative to turn said ratchet wheel and thereby elfect movement of said control device after a predetermined actuation of said cross feed mechanism, and means being also provided to vary the amount of feed at each actuation of said feed pawl.

3. In a grinding machine having a table, mechanism for reciprocating said table and a control device therefor, a grinding wheel and cross feed mechanism therefor in combination, means to actuate said cross feed mechanism to feed said grinding wheel, mechanical control mechanism rendered operative by a predetermined operation of said cross feed mechanism and effective to cause subsequent movement of said control device and to thereby modify the table travel, said control mechanism including a ratchet wheel having a blank portion thereon, a regularly actuated feed pawl periodically engaging said blank portion, and an auxiliary feed pawl intermittently operative to advance said ratchet wheel to remove the tion from under the regular feed pawl.

' 4:. In a grinding machine having a table, mechanism for reciprocating said table and a control device therefor, a grinding wheel and cross feed mechanism therefor, in combination, means to actuate said cross feed mechanism to feed said grinding wheel, me chanical control mechanism rendered operative by a predetermined operation of said cross feed mechanism and effective to cause blank por subsequent movement; of, saidcontrol device:-

having a blanlti'portion thereon,a; regularly:-v

actuated; feed: pawl-1 periodically engaging. said blankportioman; auxiliary feed pawl, andmea-ns on said crossfeed mechanism ef fective to render said-auxiliary feed pawl operative to advance, said, ratchet wheel to; remove the blank'portionfrom under the, regular feed pawh I i 5..In aigrindingmachine having a table, mechanism for reciprocating; said, table-- and: a control;devicetherefor, a grinding; wheel and cross feed mechanism therefonjincombinatiom, means to: actuate,- said; crossv feed; mechanism to feed said grinding; wheel, mechanical control mechanism rendered; ope1'-- ative by. a predetermined operation of said cross feed, mechanism, and effective to. causes subsequent movement; of saidcontrol device; and to thereby modify the table travel, said. control mechanism including acontinuously-i rotated reverse feed shaft, a clutch, andrcam; controlled means .to actuate-said clutch to connect said shaft to said cross feedmechai: nis'm and-;to,-disconnect said clutch after: a; predetermined reverse-actionof said cross: feed mechanism, saidcamrcontrolled means including relatively adjustable cam blocks, by adjustmentof which the period of: reverse actuation of said crossfeedtmechanismi may be variably determined' 6. In a grinding machine having a table, mechanism for reciprocating said table and a control device therefor, a grinding wheel and cross feed mechanism therefor, in combination, means, to actuate said cross feed mechanism to feed said grinding wheel, mechanical control mechanism rendered operative by a predetermined operation of said cross feed mechanism and effective to cause subsequent movement of said control'device and to thereby modify the table travel, and a connecting member positioned between said control mechanism and said control device, said connecting member comprising telescoping parts and a removable member for securing said parts together.

7. In a grinding machine, a cross feed mechanism including a ratchet Wheel and a feed'pawl, means to regularly actuate said feed pawl, means effective to raise said pawl to inoperative position, means to reversely rotate the ratchet wheel, and means to there after release said pawl by apredetermined manual advance rotation of said ratchet wheel. I

8. In a grinding machine, a cross feed mechanism including a ratchet Wheel and a feed pawl, means to regularly actuatesaid feed pawl, cam means effective to raise said pawl to inoperative position, means to reversely rotate said ratchet wheel, and vmeans to thereafter release said pawl by a subsequent predetermined manual advance rotation of said ratchet wheel.

9.In a" grinding machine, a cross feed 'mechanism including a ratchetwhe'el and a 'fifeed pawl, means to regularly actuate said feed pawl, cam means eifective to raise'said pawl to inoperative positiommeans to rotate said ratchet wheel in a reverse direction, means to thereafter disable said cam means '10 by a predetermined manual rotation of said ratchet wheel in an advance direction, and means to thereafter restore said cam means to condition for operation. I 10. In a grinding machine having a 15 ratchet wheel and a feed pawl, a pawl lifting device comprisinga rotatable c'amhaving high and low spots,a rock shaft, an arm on said shaft, a roll on'said' arm engaging said cam, connections from said rook shaftto said pawl, and means to move said shaft axially to removesaid cam roll from engagement witha highjspot onsaid c'am-andto' simultaneously render said connections inoperative. I r "11. The combination ina grinding machine asset forth in claim 10,in which a spring is provided effective to move said rockshaftan ularly when it is shifted axially and to bring said roll in alignment with 30 the side of the high part of said cam.

- In testimony whereof I have hereunto affixed my'signaturea PETER PLANTINGA. 

